Wireless communications capabilities are increasingly being integrated into portable devices, including laptop computers, handheld devices (such as personal digital assistants (PDAs)), and mobile phones. The integration of such capabilities can provide users with anywhere and anytime connectivity to information resources.
Power consumption is a key feature for such devices. For instance, lower power consumption levels correspond to increased operational times between battery charging sessions. As a result of this, a device user's experience may be enhanced.
Wireless networks may employ media access techniques that are based on carrier sensing. For example, networks provided by the Institute for Electrical and Electronics Engineers (IEEE) 802.11 standards may use carrier sense multiple access with collision avoidance (CSMA/CA). In CSMA/CA, a device desiring to transmit first “listens” to a channel. By listening, the device determines whether the channel is “idle” or “busy”. If the device determines that the channel is idle, then it may send its transmission. However, if the device determines that the channel is busy, then it defers its transmission.
Unfortunately carrier sensing techniques, such as those used to perform CSMA/CA, are not power-efficient.